﻿function intval(v) { 
  v = parseInt(v); 
  return isNaN(v) ? 0 : v; 
} 

function getPos(e) { 
  var l = 0; 
  var t  = 0; 
  var w = intval(e.style.width); 
  var h = intval(e.style.height); 
  var wb = e.offsetWidth; 
  var hb = e.offsetHeight; 
  while (e.offsetParent){ 
    l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0); 
    t += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0);
    e = e.offsetParent; 
    } 
    l += e.offsetLeft + (e.currentStyle?intval(e.currentStyle.borderLeftWidth):0);
    t  += e.offsetTop  + (e.currentStyle?intval(e.currentStyle.borderTopWidth):0); 
    return {x:l, y:t, w:w, h:h, wb:wb, hb:hb};
} 

function getScroll()  { 
    var t, l, w, h; 
    if (document.documentElement && document.documentElement.scrollTop) {
        t = document.documentElement.scrollTop;
        l = document.documentElement.scrollLeft;
        w = document.documentElement.scrollWidth;
        h = document.documentElement.scrollHeight;
    } 
    else if (document.body) { 
        t = document.body.scrollTop; 
        l = document.body.scrollLeft; 
        w = document.body.scrollWidth; 
        h = document.body.scrollHeight; 
    } 
    
    return { t: t, l: l, w: w, h: h }; 
}

function scroll2anchor(el, duration) {
    if(typeof el != 'object') { el = document.getElementById(el); } 
    if(!el) return; 
    
    var z = this; 
    z.el = el; 
    z.p = getPos(el); 
    z.s = getScroll(); 
    z.clear = function(){
        window.clearInterval(z.timer);
        z.timer=null
    }; 
    
    z.t=(new Date).getTime(); 
    z.step = function(){ 
        var t = (new Date).getTime();
        var p = (t - z.t) / duration; 
        if (t >= duration + z.t) { 
            z.clear(); 
            window.setTimeout(function(){z.scroll(z.p.y, z.p.x)},13);
        } 
        else { 
            st = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.y-z.s.t) + z.s.t;
            sl = ((-Math.cos(p*Math.PI)/2) + 0.5) * (z.p.x-z.s.l) + z.s.l; 
            z.scroll(st, sl); 
        } 
    };

    z.scroll = function(t, l) { window.scrollTo(l, t) }; 
    
    z.timer = window.setInterval(function(){z.step();},13);
}